If you were to get something too specialist there's a good chance she won't know how to use it and it'll just gather dust, and if you get something basic you know she can use, it's about as special a present as printer cartridges.
Are there no other interests she has you could consider?
I suppose it depends, I work as an illustrator and I'm very choosy about the materials I use, I wouldn't expect anyone else to be able to pick something for me and it seems to be that way for a majority of people I speak to.
I also don't think most boxed sets and gift packs are good value for money at all, they're always ridiculously high priced.
I suppose if your friend is just dabbling in vaguely artsy stuff as a hobby, a pack of paints or something will give them something to try, but if they're taking it seriously then you're either highly likely to buy the wrong thing, or as >>2728 said, it'll just be something utilitarian and possibly quite boring.
What you could do however is get something like an Etch a Sketch or a Munny or some other shit, something that people of all skill levels could enjoy and you won't have as much danger of getting the wrong thing.